1. Field of the Invention
The invention relates to a valve apparatus.
2. Description of Related Art
A fuel cell vehicle is equipped with a valve apparatus that controls supply of hydrogen gas from a gas tank to a fuel cell and interruption of the supply. An example of such a valve apparatus is a valve apparatus described in Japanese Patent Application Publication No. 2011-89569 (JP 2011-89569 A). The valve apparatus described in JP 2011-89569 A includes a body with a supply passage that communicates with the gas tank and a solenoid valve housed in the body. The solenoid valve has a tubular sleeve internally having a flow passage leading to the supply passage in the body, an opening and closing portion that opens and closes the flow passage in the sleeve, and a driving portion that drives the opening and closing portion so as to open and close the opening and closing portion. A downstream side opening of the flow passage in the sleeve is positioned inside the body. Inside the body, a feeding passage is formed which penetrates the body from the opening of the sleeve to an outer surface of the body. That is, high-pressure hydrogen gas contained in the gas tank is introduced into the solenoid valve via the supply passage in the body. Then, upon passing through the opening and closing portion of the solenoid valve, the gas is fed out from the opening in the outer surface of the body via the flow passage in the sleeve and the feeding passage in the body and supplied to the fuel cell. Furthermore, a seal member is disposed between an outer wall of the sleeve and an inner wall of the body. The seal member inhibits the gas in the supply passage from flowing into the feeding passage via a clearance between the sleeve of the solenoid valve and the body.
In the valve apparatus described in JP 2011-89569 A, normally, a gas pressure in the supply passage in the body is higher than a gas pressure in the feeding passage, and thus a pressure (positive pressure) based on this state is applied to the seal member. However, a pressure different from the positive pressure may be applied to the seal member depending on a variation in the gas pressure in the feeding passage. The pressure different from the positive pressure is, for example, a pressure that develops when the gas pressure in the feeding passage exceeds the gas pressure in the supply passage (counter pressure) or a pressure that develops when the gas pressure in the feeding passage rapidly decreases below the gas pressure in the supply passage (rapid decompression). When the pressure based on such a counter pressure or rapid decompression is applied to the seal member, a high load is imposed on the seal member. This leads to a shortened life of the seal member.